Selenium at low levels is an essential human nutrient, but at higher levels, human exposure to selenium can cause both short and long term health effects. Short term effects include changes to hair and finger nails, damage to the peripheral nervous system, and increased fatigue and irritability. Long term exposure to selenium has been linked to loss of hair and fingernails, damage to kidney and liver tissues, and damage to the nervous and circulatory systems. Thermo Fisher ICE-3500 原子吸收光譜儀